Locking device

ABSTRACT

AN ELECTRICALLY DRIVEN APPARATUS HOUSED IN A CABINET OR CASING WITH A DOOR HAS AN ELECTRICALLY OPERATED DOOR LATCH WHICH IS HELD LOCKED BY THE VOLTAGE DEVELOPED BY THE MOTOR DURING BRAKING OF THE APPARATUS. A REGENERATIVE BRAKING RESISTOR IS PROVIDED, IN LAUNDRY EQUIPMENT THIS   MAY BE THE WATER HEATING ELEMENT. VARIOUS SWITCHING ARRANGEMENTS ARE DESCRIBED.

P 1971 R. N. REDFEARN ETAL 3,608,331

LOCKING DEVICE Filed on. 28, 1969 ,4 Sheets-Sheet 1 INVENTORs ROBE]? 7' NEVILLE HEUl-f/IHN, HARE Y zumma/v am nw/v,

A 7 TOP/YE Y5 R. N. REDFEARN E'I'AL 3,608,337

Sept. 28, 1971 LOCKING DEVICE 4 Sheets-Sheet 2 Filed Oct. 28. 1969 INVENTORS ROBERT NEVILLE REDFEWAN, hflR/P Y DAWSON I04 TK/A/ ywm/f A TTORA E Y5.

Sept. 28, 1971 REDFEARN EI'AL 3,508,331

LOCKING DEVICE Filed Oct. 28, 1969 4 Sheets-Sheet 3 INVENTORS.

Unitecl States Patent Ofice 3,608,337 Patented Sept. 28, 1971 3,608,337 LOCKING DEVICE Robert Neville Redfearn and Harry Dawson Watkin, Huyton, Liverpool, England, assignors to Fisher-Bendix Limited, Kirkby, near Liverpool, Lancashire, England Filed Oct. 28, 1969, Ser. No. 871,892 Claims priority, application Great Britain, Oct. 31, 1968, 51.696/68, 51,697/68; Feb. 26, 1969, 10,363/69 Int. Cl. D06f 37/42 US. Cl. 68-12R 9 Claims ABSTRACT OF THE DISCLOSURE An electrically driven apparatus housed in a cabinet or casing with a door has an electrically operated door latch which is held locked by the voltage developed by the motor during braking of the apparatus. A regenerative braking resistor is provided, in laundry equipment this may be the water heating element. Various switching arrangements are described.

This invention is for improvements in or relating to cabinets or casings housing electrically driven machinery and especially locking means for the doors thereof.

The invention is particularly although not exclusively concerned with a locking means for the door of a washing machine.

There are many machines, comprising a cabinet or casing housing rotating machinery, in which it is important that access to the interior of the cabinet should be precluded until the machinery has come to rest or its speed of rotation has fallen to a safe limit. If this precaution is not taken then there is risk of injury to a person using the machine. A washing machine is a typical example, the rotating machinery being in this case a cylinder or drum which is rotated at high speed particularly during the final or dying stage of the clothes washing programme. Following this final stage the washed articles have to be removed and it is important that it should not be possible to open the door of the machine to do this until the speed of rotation of the cylinder or drum has fallen to a safe limit.

According to the present invention there is provided a cabinet or casing for electrically driven machinery, having a door, a lock for said door, an electrically energised device for retaining said lock in its door locking state and means for causing an electric driving motor for said machinery to operate temporarily as a generator when it is switched off and to supply electric current to said device for retaining the lock in its door locking state whereby the door cannot be opened until the speed of said machinery has fallen to a safe limit.

In the case of, for example, a washing machine, the electrically energised device of the door lock will, in the usual way, be maintained in its door locking state by an electricity supply from the mains during normal operation of the machine. When the mains supply is switched oif, for example by a programme unit at the end of an operating period, the electric driving motor can operate temporarily as a generator for maintaining a supply of current to the door locking device until eventually the speed of rotation of the motor and therefore of the washing cylinder drum has fallen to a safe limit at which time the device will become de-energised and permit the door to be opened.

A load resistor can be included in the motor circuitry when it is temporarily switched to operate as a generator for regenerative braking and for the supply of maintaining current temporarily to the door locking device. This load resistance may be an electric heating element or elements of the washing machine.

One particular embodiment of the invention will now be described, by way of example, as applied to a clothes washing or like machine.

The machine is of the kind comprising a cabinet within which there is a tub housing a cylinder or drum which is rotated by an electric motor at a higher speed particularly during the rinsing and/or drying period of the washing cycle. A wide variation of drum speeds can now be achieved by using a thyristor controlled direct current series motor. The cabinet is provided with a glass-fronted door for the introduction of the clothes, to be washed into the cylinder or drum and their subsequent removal therefrom. The door has an interlock device which is held in its locking position by a solenoid connected to the supply so as to be energised so long as current is supplied to the driving motor for the drum.

Regenerative braking of the drum or cylinder at the end of the washing programme is achieved by shunting the field and the armature of the motor, disconnecting the supply from the control thyristor and running the motor as a generator using, initially, the residual magnetism of the field.

For the purpose of the present invention, the solenoid coil of the door interlock, referred to above, can be connected in parallel with a brake load resistor. Sufficient voltage is available across this resistor to keep the solenoid coil energised, after switching off the machine, until the drum speed has fallen to something of the oder of 50 revolutions per minute. At this speed the solenoid coil is de-energised (i.e. there is not sufiicient voltage across the resistor to keep it energised), and the door of the cabinet can then be opened by which time it will be safe to remove the clothes from the drum or cylinder.

The accompanying drawings are circuits diagrams, of electrically operated washing machines, which include embodiments of door locking safety systems, according to the invention, for motors using tapped and untapped field windings. In the drawings:

FIG. 1 shows a tapped field, reversing armature, load resistor braking arrangement,

FIG. 2 shows a tapped field, reversing armature, load resistor braking arrangement in which a water heating element of the washing machine is also utilised as the load resistor during regenerative braking,

FIG. 3 shows an untapped field, reversing field, load resistor braking arrangement,

FIG. 4 shows an untapped field, reversing armature, load resistance braking arrangement in which a Water heating element of the washing machine is utilised as the load resistor,

FIG. 5 shows a tapped field, reversing field, load resistor braking arrangement,

FIG. 6 shows a tapped field, reversing field, load resistor braking arrangement in which a water heating element of the washing machine is utilised as the load resistor, and

FIG. 7 illustrates a modification wherein the control signal is applied over two lines neither of which are elfectively earthed.

An armature A and a field winding S4 of a drum drive direct current series-connected motor are connected in series through interconnections across two terminals T2 and T3 of a control C1 which also has a neutral connection T1. The interconnections include a forward-reverse switch S1, a wash spin speed selector S2 (in FIGS. 1 to 6 only) and a normal-braking switch S3. The switch S3 is actuated by a no-volt relay C2 connected between line potential wire L and neutral terminal T1. A door latch solenoid C3 for operating a door lock is normally connected in parallel with the relay C2 and there is a braking resistor S (which can be a water heating element)- The door latch solenoid can be designed to have a W pull-off force (the pull on force can be high but this is unimportant).

In FIGS. 1 to 6 terminal T2 is at earth potential but in FIG. 7 terminals T2 and T3 are fed by a rectifier bridge inside the control C1 and neither are effectively earthed in normal running. The use of a bridge gives greater flexibility of control and enables the speed selectors S2 to be dispensed with.

In FIGS. 2, 4, 6, and 7 the load resistor S5 is a Water heater element provided basically for heatin the washing water in the machine. In normal running this is connected to the neutral terminal T3 and to the line potential wire L through co-operating contacts 38, 39 connected together by a float or other water level sensor so that the element is not energised in the absence of water and through co-operating controls 36, 37 operated by a programme device. During braking these contacts 36, 37 and 38, 39 are by-passed.

The circuits and switches are best described by the circuit diagrams and relating the various functional configurations provided by the switches. The reference numerals on the drawings are to identify the various routes to the armature A on operation of the switches.

Referring to FIG. 1 for wash speed in the forward direction the forward-reverse switch S1 is in a position F, the wash/spin selector S2 is in position W and the brake relay switch S3 in a position N. The circuit is from T3 to 1, 2, 4 to 21 inclusive and to T2.

For wash speed in the reverse direction the reversing switch now changes to R the other switches remaining in the same condition as for the forward direction. The circuit is from T3 to 1, 2, 4, 5, 22, 23, 18, to 7 inclusive 24, 20, 21 and to T2.

For spin speed the wash/spin selector changes to position S. This allows the reversing switch to be by-passed. The braking relay contacts remain at N. The circuit is from T3 to 1, 2, 3, 25, 9 to 16 inclusive 26, 21 and to T2.

For braking the relay is de-energised and the contacts changed to B. The wash/spin selector remains at S. The armature-field shunt circuit is then from T3 to 1, 2, 4, 5, 22, 28, 14 to 11 inclusive 27, 34, 33, 32, 1 and to T3. The placing of the door-interlock solenoid coil in parallel with the braking resistor is by 34, 31, 29, 39, 40, 41, 38 and T1 to T3 inside the control C1.

Referring now to the arrangement shown in FIG. 2, for wash speed in the forward direction the reversing switch is in position F, the wash/spin selector is in position W and the relay contacts are in position N. The circuit is then from T3 to 1, 3, 4, to 20 inclusive and to T2.

For wash speed in the reverse direction the reversing switch is in position R. The circuit is then from T3, to 1, 3, 4, 21, 22, 17, to 6 inclusive, 23, 19, 20, and to T2.

For spin speed the Wash/spin selector is in position S. The circuit is then from T3 to 1, 2, 24, 8 to 15 inclusive, 25, and to T2.

For braking the wash/spin selector is at S and the brake relay contacts are in position B. The armature-field shunt circuit is then from T3 to 1, 3, 4, 21, 27, 13, 12, 11, 10, 26, 31, 32, 33, 34, 35 to T1 and inside control C1 to T3. The interlock solenoid parallel circuit with heating element is from 31 to 28, 45, 46, 47 to N and inside control C1 to T3.

In the circuit shown in FIG. 3, for wash speed in the forward direction the reversing switch is in position F, the wash/ spin selector is in position W and the relay con tacts are in position N. The circuit is then from T3 to 1 to 20 inclusive and to T2.

For wash speed in the reverse direction the reversing switch is in position R. The circuit is then from T3 to 1 to 4 inclusive, 21, 22, 23, 17 and 6 inclusive, 24, 19, 20 and to T2.

For spin speed the wash/spin selector is in position S and the relay contacts are in position N. The circuit is then from T3 to 1 to 4 inclusive 21, 25, 8 to 15 inclusive, 26, 20 and to T2.

For braking the wash/spin selector is at S and the relay contacts are in position B. The armature-fiield shunt circuit is then from T3 to 1-4 inclusive, 21, 22, 28, 12 to 10 inclusive, 27, 32, 33, 34, 1 and to T3. The interlock solenoid parallel circuit with braking resistor is from 32 to 31, 29, 38 to 41, T1 to T3.

The circuit shown in FIG. 3 may be modified for a reversing armature arrangement by connecting the field across 2 and 3 and the armature across 11 and 12.

Referring now to the circuit shown in FIG. 4 for wash speed in the forward direction the reversing switch is in position F, the wash/ spin selector is in position W and the relay contacts are in position N. The circuit is then from T3 to 1 to 19 inclusive to T2.

For wash speed in the reverse direction the reversing switch is in position R. The circuit is then from T3 to 1, 2, 3, 20, 21, 22, 16, to 5 inclusive, 23, 18, 19 and to T2.

For spin speed the wash/spin selector is in position S. The circuit is then from T3 to 1, 2, 3, 20, 24, 7 to 14 inclusive, 25,, 19 and T2.

For braking the wash/spin selector is at S and the relay contacts are in position B. The armature-field shunt circuit is then from T3 to 1, 2, 3, 20, 21, 27, 12 to 9 inclusive 26, 31 to 35 inclusive T1, to T3. The interlock solenoid parallel circuit with heater element is from 31, to 30, 28, 45, 46, 47, T1 to T3.

The circuit shown in FIG. 4 may be modified for a reversing field arrangement by connecting the armature across 1 and 2 and the field across 10 and 11.

Referring now to the circuit shown in FIG. 5, for wash speed in the forward direction the reversing switch is in position F, the wash/spin selector is in position W and the relay contacts are in position N. The circuit is then from T3 to 1 to 21 inclusive and to T2.

For wash speed in the reverse direction the reversing switch is in position R. The circuit is then from T3 to 1 to 4 inclusive, 22, 23, 24, 18 to 6 inclusive, 25, 20, 21 and T2.

For spin speed the wash/spin selector is in position S. The circuit is then from T3 to 1 to 4 inclusive, 22, 26, 8 to 12 inclusive 42, 27, 21 and T2.

For braking the wash/spin selector is in position S and the relay contacts are in position B. The armature field shunt circuit is then from T3 to 1, 35, 34, 33, 28, 10 to 14 inclusive, 29, 23, 22, 4 to 1 inclusive and to T3. The interlock solenoid parallel circuit with the brake load resistor is from 33 to 32, 30, 36 to 38 inclusive, T1 to T3.

Referring now to the circuit shown in FIG. 6, for wash speed in the forward direction the reversing switch is in position F, the wash/spin selector is in position W and the relay contacts are in position N. The circuit is then from T3 to 1 to 20 inclusive and to T2.

For wash speed in the reverse direction the reversing switch is in position R. The circuit is then from T3 to 1, 2, 3, 21, 22, 23, 17 to 5 inclusive, 24, 19, 20 and to T2.

For spin speed the wash/ spin selector is in position S. The circuit is then from T3 to 1, 2, 3, 21, 25, 7 to 11 inclusive 27, 26, 20 and to T2.

For braking the wash/ spin selector is in position S and the relay contacts are in position B. The armature-field shunt circuit is then from T3, to 1, 2, 3, 21, 22, 29, 13 to 9 inclusive 28, 33 to 35 inclusive 40, 41, T1 to T3. The interlock solenoid parallel circuit with the heater element is from 33 to 32, 30, 47, 48, 49, 46, 41 to T1 and via the control to T3. This control is the electronic speed control for the electric motor and has its terminal T3 joined to the neutral terminal T1 via in effect two resistors of low ohmic value (e.g. of the order of 0.05 ohm each) during the braking mode. The T1, T2 and T3 terminals can, therefore, be regarded as being at the same potential, for the purpose of illustration; it is to be understood however that a current is delivered between T2 and T3 in normal running. During regenerative braking, it is to be noted that the aramture or field connections are reversed to prevent damage to semiconductors in the control.

The embodiment of FIG. 7 differs from those of FIGS. 1 to 6 in that a rectifier bridge is used in the control. The use of a rectifier bridge enables a smoother wider-range progression of control so that a wash spin selector S2 is not required. However the output terminals of the bridge operate in push-pull so neither is effectively at earth potential and the bridge cannot accept regenerated currents without possible damage to semi-conductors therein.

The circuit diagram of FIG. 7 shows a series connected direct current motor consisting of an armature A and a field winding S4. An externally actuated relay S1 operates contacts to reverse the connections to the armature A (or if desired the field winding S4) under the control of a suitable timing circuit. A variable direct current supply for the motor is obtained from a controlled full wave rectifier module M1 in the control C1 to regulate the speed of the motor.

The rectifier module M1 is powered by an alternating current mains supply having line and neutral connections (L and T1 respectively). This mains supply is connected across a heater S through contacts 36, 37 and contacts 38, 39 which are operated respectively, in response to an external programme signal and in response to a Water level signal. In parallel with the heater across the mains supply there are a door latch solenoid C3 and a braking relay C2 (not shown). This braking relay is normally energised but on a programmed machine switch off or a fault in the mains supply disconnects the motor from the rectifier module and reconnects the motor across the heater. At the same time another set of contacts disconnects the door latch solenoid C3 from the now dead mains supply and reconnects it to the alternative power source provided by the regenerative braking of the motor, that is the door latch solenoid is connected in parallel with the heater.

To wash or spin in the forward direction, the braking relay contacts are at N and the reversing switch contacts are at F. The circuit is from T2, through 2 to 13 inclusive to T3.

For washing the reverse direction, the reversing switch is put to R. The circuits is from T2 through 2 to 4, 15, 9 to 6, 16, 11, to 13 and T3.

For braking, the reversing switch is returned to F and the braking relay is put to B. The circuit is 3 to 12, 18, 23, 24, 17 back to 3 with an ancillary door interlock solenoid circuit across 23 and 24 through 19, 21 and 22.

In some cases a heater may not be employed in the machinery or it may be desired to use a separate braking resistor; the circuit is the same but the connection containing contacts 36, 37 and 38, 39 is omitted.

It will be appreciated that in this circuit, the rectifier module will be completely isolated from the motor during regenerative braking and thus the rectifiers therein 6 are protected from damage. In the circuit as shown With the braking contacts immediately adjacent the module, no more contacts are needed on either relay than were used in the corresponding relays of FIGS. 1 to 6.

A similar arrangement can be devised to completely isolate the rectifier module if a tapped field motor is used but because of the flexibility of a controlled full wave rectifier a tapped field motor will not normally be required.

We claim:

1. A cabinet for electrically driven machinery, having a door, a lock for said door, an electrically energised device for retaining said lock in its door locking state, and means for causing an electric driving motor for said machinery to operate temporarily as a generator when it is switched off and to supply electric current to said device for retaining said lock in its door locking state whereby the door cannot be opened until the speed of said machinery has fallen to safe limit.

2. A cabinet according to claim 1 wherein said device is arranged to be connected across a power supply when the motor is switched on and to be reconnected by said means across the motor when the motor is switched 011?.

3. A cabinet according to claim 1 wherein said means incorporates a resistor and contacts for connecting said resistor across the motor for regenerative braking.

4. A cabinet according to claim 3 wherein the resistor is a heating element normally connected to a power supply.

5. A cabinet according to claim 4 having a semi-conductor variable speed control normally connected in series with said motor for the energization thereof.

6. A cabinet according to claim 5 having a control with two terminals supplying a variable current to the motor which is a direct current series connected motor.

7. A cabinet according to claim 6 wherein said means reverses the connections to the field winding or armature of the motor during braking to prevent reverse voltage applied to the control.

8. A cabinet according to claim 7 wherein the control incorporates controlled rectifiers.

9. A cabinet according to claim 6 wherein the control has a rectifier bridge output and said means disconnects the motor completely from said bridge output.

References Cited UNITED STATES PATENTS 1,203,567 11/1916 Bartholomew et al. 192-136 2,936,892 5/1960 McNeil et al. 68-l2(R)X 3,307,042 2/1967 Fogleman 307252.73 3,388,410 6/1968 Marshall 6824X 3,408,834 11/1968 McMillan 68--23X WILLIAM I. PRICE, Primary Examiner P. R. COE, Assistant Examiner U.S. Cl. X.R. 

